請問焦距200mm同300mm有幾大分別?

想睇唔同焦距的放大程度可以去永成攞份Tamron鏡頭catalogue.

http://www.dcfever.com/photosharing/photos/20070701/l430001183336407.jpg"

300mm其實唔長得200mm好多.如果因為咁買多支鏡可能會冇乜意欲帶佢出街.
介紹你用Tokina小鋼炮. AT-X 840 D 80-400mm F4.5-5.6, 輕便得來光圈唔太細
較平的選擇有Sigma 135-400mm F4.5-5.6,但係會重小小.
如果唔計錢當然係Canon 100-400L F4.5-5.6 IS,即係好出名既大白喇

Tokina
http://www.dcfever.com/lens/lens.php?lensid=243

Sigma
http://www.dcfever.com/lens/lens.php?lensid=113

Canon
http://www.dcfever.com/lens/lens.php?lensid=62

200mm Angle of View (diagonal) 12°
300mm Angle of View (diagonal) 8°